<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>

</body>
<script>
    setTimeout(() => {
        console.log(0);
    }, 0)
    new Promise((resolve, reject) => {
        console.log(1);
        resolve()
    }).then(() => {
        console.log(2);
        new Promise((resolve, rejext) => {
            console.log(3);
            resolve()
        }).then(() => {
            console.log(4);
        }).then(() => {
            console.log(5);
        })
    }).then(() => {
        console.log(6);
    })

    new Promise((resolve, reject) => {
        console.log(7);
        resolve()
    }).then(() => {
        console.log(8);
    })

    // 控制台输出顺序  1,7,2,3,8,4,6,5,0
</script>

</html>